1. Field of the Invention
The present invention relates to an optical recording medium and a method of manufacturing the optical recording medium.
2. Description of the Related Art
In recent years, attention has been paid to an optical recording medium as a high density recording medium.
FIG. 1 is a sectional view showing a conventional example of an optical magnetic recording medium of the optical recording medium.
The optical magnetic recording medium has such a structure that a dielectric film 3, a recording film 4 formed of a magnetic film, a dielectric film 5 and a reflective film 6 formed of a metal are sequentially layered on a transparent substrate 2 composed of polycarbonate or the like for example. A laser beam 9 is irradiated from the transparent substrate 2 side to record and reproduce a signal.
On the other hand, the following optical magnetic recording medium has been developed for higher density recording.
This is such that, for example, a reflective film, a dielectric film, a recording film, a dielectric film and an organic protective film are sequentially layered on a substrate. A laser beam is irradiated from the organic protective film side opposite to the substrate for recording and reproducing a signal (hereinafter referred to as a xe2x80x9csurface reading optical magnetic recording mediumxe2x80x9d).
In the surface reading optical magnetic recording medium, however, disk noises such as an erasing noise, a recording noise and the like are disadvantageously made greater than those in the conventional optical magnetic recording medium for recording and reproducing by laser beam irradiation from the transparent substrate side.
In the optical magnetic recording medium, the recording noise is made by the reproduction after converging and irradiating a laser beam to perform recording while giving a magnetic field from the outside at a constant frequency.
The erasing noise is a DC erase noise which is made when reproduced a signal after converging and irradiating a laser beam to erase a recorded signal while giving a magnetic field from the outside in one direction.
In consideration of such a problem, it is an object of the present invention to provide an optical recording medium capable of reducing disk noises such as the erasing noise, the recording noise and the like and a method of manufacturing the optical recording medium.
The present invention provides a method of manufacturing an optical recording medium in which light is irradiated from an opposite side to a substrate, thereby causing recording and/or reproduction on a recording film to be carried out, comprising the steps of preparing a substrate, forming a reflective film on the substrate, carrying out a smoothing treatment on a surface of the reflective film and forming a recording film on the reflective film.
Moreover, the present invention provides a method of manufacturing an optical recording medium in which light is irradiated from an opposite side to a substrate, thereby causing recording and/or reproduction on a recording film to be carried out, comprising the steps of preparing a substrate, sequentially forming a reflective film and a dielectric film on the substrate, carrying a smoothing treatment on at least one of surfaces of the reflective film and the dielectric film and then forming a recording film on the dielectric film.
Furthermore, the present invention provides an optical recording medium in which at least a reflective film and a recording film are formed on a substrate and light is irradiated from an opposite side to the substrate for carrying out recording and/or reproduction on the recording film, wherein the reflective film has a surface roughness Ra of 0.75 nm or less.
Moreover, the present invention provides an optical recording medium in which at least a reflective film, a dielectric film and a recording film are sequentially formed on a substrate and light is irradiated from an opposite side to the substrate for carrying out recording and/or reproduction on the recording film, wherein the dielectric film has a surface roughness Ra of 0.75 nm or less.
According to the optical recording medium and the method of manufacturing the same in accordance with the present invention, the surface of the reflective film is subjected to the smoothing treatment. Therefore, it is supposed that scattered light on the reflective film can be reduced.
According to the optical recording medium and the method of manufacturing the same in accordance with the present invention, at least one of the surfaces of the reflective film and the dielectric film is subjected to the smoothing treatment. Consequently, it is supposed that the scattered light on the reflective film can be reduced and/or magnetic characteristics can be enhanced by flattening the recording film.